SUMMARY A fundamental feature of a living system is its integrated network of biochemical pathways that respond to endogenous stresses as well as those applied by the environment. Microbes, particularly those with a well- developed genetic system, provide a unique opportunity for the characterization of stress responses that have evolved to control reactive metabolites generated by metabolic processes. Metabolic strategies are conserved across biology, and insights obtained from microbial systems provide the means to advance our understanding of general metabolic paradigms. The long-term goal of the PI's research is to understand the robustness and redundancy of the metabolic network, and to define metabolic components and the processes they participate in. A rigorous understanding of metabolic processes is critical to efforts aimed at predicting how cells respond to environmental change, to efforts aimed at treating metabolic diseases, and to efforts targeting metabolism for rational drug design and/or production of value chemicals, to name a few. The goal of the work proposed herein is to characterize a metabolic stress that results form reactive metabolites generated during growth and to understand the family of proteins that neutralize this stress. This study focuses on the highly conserved Rid protein family, and the founding bacterial member RidA. In the current proposal we will: i) further our understanding of the mechanism used by RidA and other family members to eliminate endogeneously generated enamine/imine stress; ii) describe additional, distinct mechanisms that have evolved to deal with similar stress; and iii) explore the breadth of this stress and how different organisms handle it. The goals of this proposal will be accomplished through the combination of chemical, biochemical, biophysical, molecular, genetic and bioinformatics approaches. The work here is motivated by our desire to understand the metabolic stress generated by the production of reactive metabolites during growth, and how it can damage cellular components if it is not neutralized.